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Fix USB image corruption issues

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Fixes FS#10614
sfdisk and the kernel cannot accurately detect
disk geometry from the disk image file, causing
automatic partition size calculations to fail.
The whole partition table is now calculated
in mkusbimg rather than letting sfdisk do it.

mkusbimg doesn't directly use losetup anymore
either, eliminating some code.

This also fixes issues with needing to make the
partition much larger than necessary, so image
size has been minimized.

Signed-off-by: Simo Leone <simo@archlinux.org>
This commit is contained in:
Simo Leone 2008-06-21 18:58:29 -05:00
parent 7315f8459d
commit a53cf77e3f
1 changed files with 28 additions and 51 deletions
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79
mkusbimg
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@ -16,25 +16,6 @@
# You should have received a copy of the GNU General Public License # You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>. # along with this program. If not, see <http://www.gnu.org/licenses/>.
# next_avail_loop()
# prints the next available loopback device
# returns 0 on success
# 1 on failure
# XXX: this is only necessary because
# the cryptoloop patch for losetup
# destroys losetup -f
next_avail_loop()
{
for i in /dev/loop/*; do
echo $(losetup -a|cut -d':' -f1) | grep -q $i
if [ $? -eq 1 ]; then
echo $i
return 0
fi
done
return 1
}
# usage(exitvalue) # usage(exitvalue)
# outputs a usage message and exits with value # outputs a usage message and exits with value
APPNAME=$(basename "${0}") APPNAME=$(basename "${0}")
@ -50,52 +31,48 @@ if [ $# -ne 2 ]; then
usage 1 usage 1
fi fi
IMG="${2}" DISKIMG="${2}"
IMGROOT="${1}" IMGROOT="${1}"
LOOPDEV=$(next_avail_loop)
TMPDIR=$(mktemp -d) TMPDIR=$(mktemp -d)
FSIMG=$(mktemp)
# TODO: there are better ways to do this # ext2 overhead's upper bound is 6%
# than adding 25% to the rootsize # empirically tested up to 1GB
# XXX: doesn't seem to boot if we cut it too
# close. even if everything fits...
# IMGSZ >= filesystem overhead + rootsize + 512bytes
# must hold or there will be insufficient space
rootsize=$(du -bs ${IMGROOT}|cut -f1) rootsize=$(du -bs ${IMGROOT}|cut -f1)
IMGSZ=$(( (${rootsize}*5)/4 + 512 )) IMGSZ=$(( (${rootsize}*106)/100/512 + 1)) # image size in sectors
# create the image file # create the filesystem image file
dd if=/dev/zero of="$IMG" bs="$IMGSZ" count=1 dd if=/dev/zero of="$FSIMG" bs=512 count="$IMGSZ"
# loop mount the disk image # create a filesystem on the image
losetup "$LOOPDEV" "$IMG" mke2fs -m 0 -F "$FSIMG"
# mount the filesystem and copy data
mount -o loop "$FSIMG" "$TMPDIR"
cp -a "$IMGROOT"/* "$TMPDIR"
# unmount filesystem
umount "$TMPDIR"
# add sectors 0-62, then glue together
dd if=/dev/zero of="$DISKIMG" bs=512 count=63
cat "$FSIMG" >> "$DISKIMG"
# create a partition table # create a partition table
# if this looks like voodoo, it's because it is # if this looks like voodoo, it's because it is
echo "63,,,*,"|sfdisk -uS "$LOOPDEV" sfdisk -uS -f "$DISKIMG" << EOF
63,$IMGSZ,83,*
# loop mount the partition we just made 0,0,00
# that magic number (offset in bytes to first partition) is more voodoo 0,0,00
losetup -d "$LOOPDEV" 0,0,00
losetup -o32256 "$LOOPDEV" "$IMG" EOF
# create a filesystem on our partition
mke2fs -m 0 "$LOOPDEV"
# mount the filesystem and copy data
mount "$LOOPDEV" "$TMPDIR"
cp -a "$IMGROOT"/* "$TMPDIR"
# unmount filesystem and loopback
umount "$TMPDIR"
losetup -d "$LOOPDEV"
# install grub on the image # install grub on the image
grub --no-floppy --batch << EOF grub --no-floppy --batch << EOF
device (hd0) $IMG device (hd0) $DISKIMG
root (hd0,0) root (hd0,0)
setup (hd0) setup (hd0)
EOF EOF
# all done :) # all done :)
rm -fr "$TMPDIR" rm -fr "$TMPDIR" "$FSIMG"